Other mistake: In the Todd-OA version, just before the song "Oklahoma." Gordon MacCrae puts his hand on the porch post and the post moves off the rail. He then pulls it back.
Continuity mistake: During the desert chase sequence, when our hero is run off the road by Ernest B. his missing arm is momentarily transposed when he steps from the jeep.
Continuity mistake: Sacajawea (Donna Reed) dives into the water to retrieve some important maps, which have fallen in and been taken to the back of the boat. When she dives in, the maps are back to the original area they fell into, when they should have been quite a distance from where they landed in the water.
Factual error: While the Confederate captain is explaining the mission, a couple of the "patriots" are inserting cartridges into their Colt Peacemakers. A neat trick, since the Civil War ended in 1865, and the Peacemaker wasn't introduced until 1873.
Factual error: When Jimmy Stewart is almost down to the runway during the bad weather, the aircraft exterior shots show the type of cloud tops found only at high altitude, not low to the ground.